python convert datetime formatted string to seconds

Question

I am trying to decode a date string to epoch but I have difficulties getting the timezone. This is the last modified date from Amazon S3 keys.

time.strptime(key.last_modified, '%Y-%m-%dT%H:%M:%S.%Z')

ValueError: time data u'2013-10-20T00:41:32.000Z' 
            does not match format '%Y-%m-%dT%H:%M:%S.%Z'

If I get rid of the timezone (.000Z) it works, but I need the timezone as well.

Answer 1

The .000Z is not recognized as a timezone offset. In fact, you have milliseconds and a timezone (Z is UTC), and officially, time.strptime() parser cannot handle milliseconds. On some platforms %f will parse the microsecond portion, then discard the information.

The datetime.datetime.strptime() class method, however, can, but not the timezone, however; parse the Z as a literal and it works:

from datetime import datetime

datetime.strptime(key.last_modified, '%Y-%m-%dT%H:%M:%S.%fZ')

Demo:

>>> from datetime import datetime
>>> import time
>>> example = u'2013-10-20T00:41:32.000Z'
>>> datetime.strptime(example, '%Y-%m-%dT%H:%M:%S.%fZ')
datetime.datetime(2013, 10, 20, 0, 41, 32)
>>> time.strptime(example, '%Y-%m-%dT%H:%M:%S.%fZ')
time.struct_time(tm_year=2013, tm_mon=10, tm_mday=20, tm_hour=0, tm_min=41, tm_sec=32, tm_wday=6, tm_yday=293, tm_isdst=-1)

Note that on my Mac OS X laptop, %f works for time.strptime(); it is not guaranteed to work everywhere, however.

Converting a datetime.datetime() object to a time tuple can be done with the datetime.timetuple() method.